Manufacturing device for electrode mixture sheet

Abstract

A manufacturing device 1 for an electrode mixture sheet S comprises a first roll 2, a second roll 4, and a third roll 6. The first roll 2 and the second roll 4 place a dry electrode mixture P on a first circumferential surface 2a of the first roll 2 and a second circumferential surface 4a of the second roll 4, supply the dry electrode mixture P to a gap between the two rolls to form an electrode mixture sheet S, and support and convey the electrode mixture sheet S on the second circumferential surface 4a. The third roll 6 transfers the electrode mixture sheet S that passes through a gap between the second roll 4 and the third roll 6 from the second circumferential surface 4a to a third circumferential surface 6a of the third roll 6, and supports and conveys the electrode mixture sheet S via the third circumferential surface 6a. With regard to at least one of the first circumferential surface 2a, the second circumferential surface 4a, and the third circumferential surface 6a, the average length RSm of a roughness curve element has a relationship of 0.5 × D50 ≤ RSm ≤ 10 × D50 with respect to the median diameter D50 of the dry electrode mixture P.

Description

Manufacturing Apparatus for Electrode Composite Agent Sheet

[0001] The present disclosure relates to a manufacturing apparatus for an electrode composite agent sheet.

[0002] Patent Document 1 describes a method for manufacturing a coated film product in which a wet electrode composite agent paint is introduced into the gap between a first roll and a second roll, and a coating film is formed on the surface of the second roll and conveyed.

[0003] Japanese Patent Application Laid-Open No. 2016-59870

[0004] Regarding the dry electrode composite agent, there are cases where it is formed into a sheet shape and conveyed using a plurality of rolls as in the above-described manufacturing method. As a result of intensive studies on a manufacturing apparatus for a dry electrode composite agent sheet, the present inventor has found a technique for improving the performance of a manufacturing apparatus such as the formability and transportability of an electrode composite agent sheet.

[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a technique for improving the performance of a manufacturing apparatus for an electrode composite agent sheet.

[0006] One aspect of the present disclosure is a manufacturing apparatus for an electrode composite agent sheet. This apparatus includes a first roll and a second roll that are adjacent to each other with a predetermined interval therebetween. A dry electrode composite agent is placed on the first circumferential surface of the first roll and the second circumferential surface of the second roll and supplied into the gap between the two rolls, and the dry electrode composite agent is compressed into a sheet shape to form an electrode composite agent sheet. The first roll and the second roll support and convey the electrode composite agent sheet on the second circumferential surface. A third roll is adjacent to the second roll with a predetermined interval therebetween. The electrode composite agent sheet passing through the gap between the second roll and the third roll is transferred from the second circumferential surface to the third circumferential surface of the third roll and supported and conveyed on the third circumferential surface. At least one of the first circumferential surface, the second circumferential surface, and the third circumferential surface has a relationship of 0.5×D50≦RSm≦10×D50, where RSm is the average length of roughness curve elements measured in accordance with JIS B 0601:2001 standard using a contact type roughness meter, with respect to the median diameter D50 of the dry electrode composite agent.

[0007] Any combination of the above components, and those obtained by converting the expression of the present disclosure among methods, apparatuses, systems, etc., are also effective as aspects of the present disclosure.

[0008] According to this disclosure, it is possible to improve the performance of the manufacturing equipment for electrode mixture sheets.

[0009] This is a schematic diagram of a manufacturing apparatus for electrode mixture sheets according to an embodiment. This figure shows the results of a transferability evaluation test.

[0010] The present disclosure will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. Furthermore, where terms such as "first," "second," etc. are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are used to distinguish one configuration from another. In addition, some components that are not important for explaining the embodiments are omitted in each drawing.

[0011] Figure 1 is a schematic diagram of an electrode mixture sheet manufacturing apparatus 1 according to an embodiment. The electrode mixture sheet manufacturing apparatus 1 comprises a first roll 2, a second roll 4, a third roll 6, and a storage section 8. Hereinafter, the electrode mixture sheet manufacturing apparatus 1 will be abbreviated as "manufacturing apparatus 1" as appropriate. In the manufacturing apparatus 1 of this embodiment, as an example, the first roll 2, the second roll 4, and the third roll 6 are arranged in the horizontal direction.

[0012] The storage section 8 has a known structure, such as a combination of a hopper and a feeder, and stores the dry electrode mixture P, which is the raw material for the electrode mixture sheet S. The dry electrode mixture P contains an electrode active material and a binder. It also contains a conductive agent and a solvent as needed. The binder and solvent function as binding components that bind the electrode active materials together.

[0013] In typical lithium-ion secondary batteries, the electrode active material is lithium cobalt oxide or lithium iron phosphate for the positive electrode, and graphite for the negative electrode. The binder is polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), etc. The conductive agent is graphite, carbon black, acetylene black, etc. When dry electrode mixture P is used as the negative electrode, the solvent is water, alcohols, N-methylpyrrolidone (NMP), toluene, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc. When dry electrode mixture P is used as the positive electrode, the solvent is amine-based solvent, ether-based solvent, ketone-based solvent, ester-based solvent, amide-based solvent, etc. As an example, the solvent content of dry electrode mixture P is 5% by mass or less, 3% by mass or less, 0.1% by mass, or substantially 0% of the total mass of dry electrode mixture P.

[0014] A first roll 2 and a second roll 4 are positioned at the powder outlet of the storage section 8. The orientation of the first roll 2 and the second roll 4 is determined so that their respective rotation axes are parallel to each other, and they are adjacent to each other with a predetermined distance between them. The second roll 4 is positioned downstream of the first roll 2 in the direction of conveying the electrode mixture sheet S. Dry electrode mixture P is supplied from the storage section 8 into the gap between the first roll 2 and the second roll 4. In this embodiment, the first roll 2 and the second roll 4 function as feed rolls. That is, the first roll 2 supplies the dry electrode mixture P from the storage section 8 into the gap between the two rolls by placing it on its first circumferential surface 2a. The second roll 4 supplies the dry electrode mixture P from the storage section 8 into the gap between the two rolls by placing it on its second circumferential surface 4a.

[0015] The first roll 2 and the second roll 4 rotate in opposite directions, compressing the dry electrode mixture P supplied into the gap into a sheet. This forms the electrode mixture sheet S. Therefore, the first roll 2 and the second roll 4 also function as forming rolls. The electrode mixture sheet S is continuously fed out from the gap between the first roll 2 and the second roll 4. Therefore, the electrode mixture sheet S is a long strip in the conveying direction. The electrode mixture sheet S is conveyed downstream while being supported by the second circumferential surface 4a of the second roll 4. Therefore, the second roll 4 also functions as a conveying roll.

[0016] A third roll 6 is positioned downstream of the second roll 4. The second roll 4 and the third roll 6 are positioned adjacent to each other with a predetermined distance between them, so that their respective axes of rotation are parallel to each other. The electrode mixture sheet S is supported and conveyed by the second circumferential surface 4a of the second roll 4 and passed through the gap between the second roll 4 and the third roll 6. The second roll 4 and the third roll 6 can feed the electrode mixture sheet S downstream by rotating in opposite directions with the electrode mixture sheet S sandwiched between them. As the electrode mixture sheet S passes through the gap between the second roll 4 and the third roll 6, it is transferred from the second circumferential surface 4a to the third circumferential surface 6a of the third roll 6 at the position where the second roll 4 and the third roll 6 face each other. The electrode mixture sheet S is then supported by the third circumferential surface 6a of the third roll 6 and conveyed downstream. Therefore, the third roll 6 functions as a conveying roll.

[0017] The electrode mixture sheet S may be stretched as it passes through the gap between the second roll 4 and the third roll 6. In other words, the second roll 4 and the third roll 6 may function as stretching rolls. For example, the second roll 4 and the third roll 6 rotate at different peripheral speeds. Specifically, the rotation speed of the third roll 6 is faster than the rotation speed of the second roll 4. This allows the second roll 4 and the third roll 6 to transport the electrode mixture sheet S and stretch it due to the difference in their peripheral speeds. Alternatively, the electrode mixture sheet S can also be stretched by making the gap between the second roll 4 and the third roll 6 narrower than the thickness of the incoming electrode mixture sheet S.

[0018] At least one of the first circumferential surface 2a, the second circumferential surface 4a, and the third circumferential surface 6a has an average length RSm of roughness curve elements such that 0.5 × D50 ≤ RSm ≤ 10 × D50 with respect to the median diameter D50 of the dry electrode mixture P. RSm is measured using a contact-type roughness tester in accordance with the JIS B 0601:2001 standard. The median diameter D50 is the particle size at which the cumulative value in the particle size distribution of the dry electrode mixture P becomes 50%, i.e., the 50% volume average particle size. D50 can be measured using a commercially available laser analysis / scattering particle size distribution analyzer. The dry electrode mixture P may be a one-particle system composed of only one type of particle with substantially equal particle size, a two-particle system composed of substantially two types of particles with different particle sizes, or a three-particle system or more.

[0019] As a result of diligent research, the inventors have found that the performance of the manufacturing apparatus 1 can be improved by adjusting the RSm of at least one of the first circumferential surface 2a, the second circumferential surface 4a, and the third circumferential surface 6a to 0.5 times or more and 10 times or less of the D50 of the dry electrode mixture P. In other words, by having the above relationship for the RSm of any of the circumferential surfaces, the adhesion between that circumferential surface and the dry electrode mixture P, and the adhesion between that circumferential surface and the electrode mixture sheet S can be improved. This makes it possible to improve the moldability and transportability of the electrode mixture sheet S in the manufacturing apparatus 1.

[0020] In particular, when the RSm of the first circumferential surface 2a has the above relationship, the dry electrode mixture P can be supplied more stably from the storage section 8 to the gap between the first roll 2 and the second roll 4. Therefore, the moldability of the electrode mixture sheet S can be improved.

[0021] Furthermore, when the RSm of the second circumferential surface 4a has the above relationship, the supply stability of the dry electrode mixture P into the gap between the first roll 2 and the second roll 4 can be improved, and the moldability of the electrode mixture sheet S can be improved. In addition, the molded electrode mixture sheet S can be stably supported by the second circumferential surface 4a. As a result, peeling of the electrode mixture sheet S from the second circumferential surface 4a can be suppressed, and the transportability of the electrode mixture sheet S can be improved.

[0022] Furthermore, when the RSm of the third circumferential surface 6a has the above relationship, the electrode mixture sheet S can be stably transferred from the second circumferential surface 4a to the third circumferential surface 6a. Also, the electrode mixture sheet S can be stably supported on the third circumferential surface 6a. Therefore, the transportability of the electrode mixture sheet S can be improved. Note that when both the RSm of the second circumferential surface 4a and the RSm of the third circumferential surface 6a have the above relationship, the electrode mixture sheet S can be transferred from the second circumferential surface 4a to the third circumferential surface 6a by setting the rotation speed of the third roll 6 to be faster than the rotation speed of the second roll 4.

[0023] Preferably, all RSm values ​​of the first circumferential surface 2a, the second circumferential surface 4a, and the third circumferential surface 6a have the above relationship. This further improves the moldability and transportability of the electrode mixture sheet S in the manufacturing apparatus 1.

[0024] The configuration of the manufacturing apparatus 1 can be modified as appropriate. For example, the arrangement direction of the first roll 2, the second roll 4, and the third roll 6 is not particularly limited. For example, the third roll 6 may be arranged vertically or diagonally with respect to the second roll 4. In addition, one or more conveying rolls may be arranged downstream of the third roll 6. Furthermore, lamination rolls may be arranged adjacent to the downstream conveying rolls. In this case, electrode mixture sheets S can be laminated onto sheet materials such as current collector plates conveyed by the lamination rolls.

[0025] The embodiments of this disclosure have been described in detail above. The embodiments described above are merely examples of how to implement this disclosure. The content of the embodiments does not limit the technical scope of this disclosure, and many design changes, such as changes, additions, and deletions of components, are possible, as long as they do not deviate from the idea of ​​this disclosure as defined in the claims. A new embodiment with design changes will have the effects of both the combined embodiment and the variation. In the embodiments described above, the content in which such design changes are possible is emphasized with notations such as "of this embodiment" or "in this embodiment," but design changes are also permitted even if there are no such notations. Any combination of components included in each embodiment is also valid as an embodiment of this disclosure. The hatching applied to the cross-section in the drawings does not limit the material of the object to which the hatching is applied.

[0026] The embodiments may be specified by the items described below. [Item 1] A first roll (2) and a second roll (4) adjacent to each other at a predetermined interval, wherein a dry electrode mixture (P) is placed on the first circumferential surface (2a) of the first roll (2) and the second circumferential surface (4a) of the second roll (4) and supplied into the gap between the two rolls (2,4), the dry electrode mixture (P) is compressed into a sheet to form an electrode mixture sheet (S), and the electrode mixture sheet (S) is supported and conveyed by the second circumferential surface (4a) of the first roll (2) and the second roll (4) A manufacturing apparatus (1) for an electrode mixture sheet (S), wherein at least one of the first surface (2a), the second surface (4a), and the third surface (6a) has an average length RSm of roughness curve elements measured using a contact roughness meter in accordance with the JIS B 0601:2001 standard, such that the relationship 0.5 × D50 ≤ RSm ≤ 10 × D50 with respect to the median diameter D50 of the dry electrode mixture (P). [Second item] The manufacturing apparatus (1) for an electrode mixture sheet (S) according to item 1, wherein the RSm of all of the first surface (2a), the second surface (4a), and the third surface (6a) has the above relationship.

[0027] The following describes embodiments of the present invention, but these embodiments are merely illustrative examples for suitably illustrating the present invention and do not limit the present invention in any way.

[0028] (Example 1) A manufacturing apparatus 1 shown in Figure 1 was prepared. The storage section 8 was filled with a dry electrode mixture P having a D50 of 9 μm. The D50 of the dry electrode mixture P was measured using a laser diffraction / scattering particle size distribution analyzer (LA-920: manufactured by HORIBA). The RSm of the first circumferential surface 2a was set to 74.88 μm, corresponding to 8 × D50. The RSm of the second circumferential surface 4a was set to 49.71 μm, corresponding to 6 × D50. The RSm of the third circumferential surface 6a was set to 79.83 μm, corresponding to 9 × D50. The RSm of each circumferential surface was measured using a contact-type roughness meter (SURFTEST SJ-210: manufactured by Mitutoyo Corporation).

[0029] The following evaluation test was performed using the manufacturing apparatus 1 according to Example 1. Specifically, an electrode mixture sheet S was formed from the dry electrode mixture P and transported, and the transferability of the electrode mixture sheet S was evaluated to see whether it could be transferred from the second circumferential surface 4a to the third circumferential surface 6a. In the evaluation of transferability, a ○ was given if the electrode mixture sheet S was transferred from the second circumferential surface 4a to the third circumferential surface 6a, and a × was given if it was not transferred. The results are shown in Figure 2.

[0030] (Example 2) An evaluation test was conducted in the same manner as in Example 1, except that the RSm of the third circumferential surface 6a was set to 57.71, which corresponds to 6 × D50. The results are shown in Figure 2.

[0031] (Example 3) An evaluation test was conducted in the same manner as in Example 1, except that the RSm of the third circumferential surface 6a was set to 28.69, which corresponds to 3 × D50. The results are shown in Figure 2.

[0032] (Comparative Example 1) An evaluation test was conducted in the same manner as in Example 1, except that the RSm of the third circumferential surface 6a was set to 94.53, which corresponds to 11 × D50. The results are shown in Figure 2.

[0033] Figure 2 shows the results of the transferability evaluation test. As shown in Figure 2, in Examples 1 to 3, where the RSm of the third circumferential surface 6a was 10 × D50 or less, the transferability was good (○). On the other hand, in Comparative Example 1, where the RSm of the third circumferential surface 6a was greater than 10 × D50, the transferability was poor (×). In Comparative Example 1, the electrode mixture sheet S remained attached to the second circumferential surface 4a even after passing through the gap between the second roll 4 and the third roll 6.

[0034] From the above, it was confirmed that by setting the RSm of the third circumferential surface 6a to 10 × D50 or less, the electrode mixture sheet S can be stably transferred from the second circumferential surface 4a to the third circumferential surface 6a, thereby improving the transportability of the electrode mixture sheet S. Furthermore, from these results, it can be understood that by setting the RSm of the first circumferential surface 2a and the second circumferential surface 4a to 10 × D50 or less, the moldability and transportability of the electrode mixture sheet S can be improved.

[0035] The arithmetic mean roughness Ra of the first surface 2a and the second surface 4a were 0.16 μm and 0.45 μm, respectively. Furthermore, the Ra of the third surface 6a in Example 1 was 0.85 μm, in Example 2 it was 0.82 μm, in Example 3 it was 0.86 μm, and in Comparative Example 1 it was 0.91 μm. Therefore, Ra was approximately the same in each example and comparative example. From this, it can be understood that the RSm of the third surface 6a greatly affected the transferability. The lower limit of RSm, 0.5 × D50, under the above conditions is the minimum value of RSm achievable in general roll manufacturing technology.

[0036] This disclosure can be used in a manufacturing apparatus for electrode mixture sheets.

[0037] 1 Manufacturing apparatus, 2 First roll, 2a First surface, 4 Second roll, 4a Second surface, 6 Third roll, 6a Third surface, P Dry electrode mixture, S Electrode mixture sheet.

Claims

A first roll and a second roll adjacent to each other at a predetermined interval, wherein a dry electrode mixture is placed on the first circumferential surface of the first roll and the second circumferential surface of the second roll and supplied into the gap between the two rolls, the dry electrode mixture is compressed into a sheet to form an electrode mixture sheet, and the first roll and second roll support and transport the electrode mixture sheet with the second circumferential surface, The system comprises a third roll adjacent to the second roll at a predetermined distance, the third roll transferring the electrode mixture sheet passing through the gap between the second roll and the third roll from the second circumferential surface to the third circumferential surface of the third roll, and supporting and conveying it on the third circumferential surface, At least one of the first, second, and third circumferential surfaces has an average length RSm of roughness curve elements measured using a contact-type roughness tester in accordance with JIS B 0601:2001, such that the relationship 0.5 × D50 ≤ RSm ≤ 10 × D50 with respect to the median diameter D50 of the dry electrode mixture. Manufacturing equipment for electrode mixture sheets. 　 All of the RSm values ​​of the first circumferential surface, the second circumferential surface, and the third circumferential surface have the above relationship. The apparatus for manufacturing an electrode mixture sheet according to claim 1.

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